Electric control circuits



April 6, 1943. 1. c. LUDBROOK 2,316,003

ELECTRIC CONTROL CIRCUIT Filed Nov. 12, 1941 5 ourPur CQNTROL CIRCUIT CIRCUIT Leslie C. Ludbrook,

His Attorney.

Patented Apr. 6, 1943 UNITEDSTA PATENT Connor. ogtilllrs f Leslie 5c,

signor 7 ration of New Application Mambo-{12, 19,41 Sen ancl nore psrticuiorly to control circuits for trolling the phase of an altcrnatlng voltagen itn respect to the voltage of an alternating current n; Great-Britain monster 1&1

near Edgin Emiss- Electric Compass)",

o'ltsge ot, a centre! circuit. Piss. Eertain modifications of my selective cnergization of the Solis obtained by employing impedallc e 'l source. -11; munidlrectionol conducting devices or rectlfiers It isirequently desirable in" systems to provide a simple is controlling the phase of on outptrtecoltogc respect tothe voltage or an associated current sources? Heretofcre the narransessc ts 1Q unlelihaebeen provided for obtaining racism icicle phase relationship have involved apparatus of o rather complicated nature and; have? not been as positive and precise inopcratlon asmsny instances required. In accordance with the teachings of my invention described hereinafter, I provide new and improved arrangement-owners by precise control of the phase and vi 'tude of output voltage is ohtsinedsisp cntplcying expensive tomanufacturer r r r r V It'ls an object of my invention to provide new and improved electrlccontrolcircults" It is another object oi'my invention to provide new and improved control circuits ror attcrnating current, systems wherein the phase of an alternating voltage is accurately controllable in response to the voltage of an associated control circuit. r

,It is a rurtlzier object of my invention to provide new and improved electric control systems wherein the phase and magnitude of an output voltage are accurately and precisely controllable" in response to the voltage of an associated con trol circuit.

Briefly stated, in the illustrated'embodlments" of my insenticnLpi-ovide new end improred ctrcult arrangements for controlling tkemfif an alternating voltage with respect to'the voltage? which are osse transmit unidirectional cur rent through the impedance elements in response to the polarity of the voltage of an associated control circuit; 31

Referring 1 of the drawing, my invention is there illustrated as applied to a bridge-type circuit for supplying to an output circuit, including conductors l and 2, an alternatlog voltage laolephasc displacement with 15 respect to tie goltsge or an associated alternat ccmprisingcfi utens l and 5. The control cirapparatus of moderate size, lessees not so cult more tine nature in which the control voltagels essence in polarity.

The bridge circuit in the arrangement of Fig. 1 "or parallel non-reactive branches eslstances 6 and 1 and nonlinear d; 8'. The nonlinear resistances 8 and 9 mar lse oonstructed of a. material such as that disclosed in United States Letters Patent I granted September 8, 1938, upon an Karl B. McEachron and which is ssignee of the present applicalcl hos a nonlinear impedance-currentcol oraoteristic. Of course, it is to be understocd thutntlgcr types of resistances may be emforreslstsnces B and 8, such as fine fila- V ulcstantialiy above the ambient tempers. t g gnfpisce of the nonlinear resistances B and i, suitable rectlfyingdevices, such as contact rectifiers or thermionic rcctlfiers, may be employed.

of on alterngt ing cg n'ent circuit t t ng 49 j c I connect across; the terminals of the control to impedance elements connected in the circuits variable amounts lot umdirectionalcnn'enti shirt inphcscor phase displacement isob'tsiioeic y fl nerimposins on the altemctioocerrs "circuit a pair of serially connected resistances M and {1, the common iuncture i: of which is conncctcd in series relation witlithc source of alternoting currentlapd a source of unidirectional of voltage derived from th o s vgmm is current l3. The source otunldirectional current appended claims" Fig; 1' dlsgrsmmgticclly mus-'7 trotes an embodiment of my invention as applied i3 is sgll ussalc'toprovide an arrangement for baloncin fifldce, that is, provides an arrangement for ,bolancingc the current transmitted through tlg e rgpectiticnssociated branches for a so given conditlon oi ti e control circuit.

The operation of the embodiment of my invention shown "3. will be explained when considering the system when it is operating to control tnelpiissogoi cthe voltage supplied to the to a bridge-type circuit which is controlled in 65 gutput circuit, including conductors I and 2, in

response to the voltage of the control circuit including conductors I and 3. The bridge circuit is initially adjusted byroontrolllng the effective or output voltage of the source of directcurrent 13. The variation in the voltage drop appearing across resistances l and ll in response to both the magnitude of the control voltage and the polarity of the control voltage buck boost the bias currents in resistances '8 and 3, thereby eiiecting an unbalance of the bridge in response to the control voltage. The phase oi the alternating current output voltage is advanced or retarded with respect to the voltage oi. tnenltematingcurrent source 3, in response to the polarityioi these voltages. Due to the ncnlinearity oi flicresistance elements 8 and 3.11 will lie that the variation in potential diiierence Mween condoctors I and 2 is aceentlmted. Inasmuch asthe resistance elements of the bridge circuit are nonreactive, neglig-lble phase shift occurs between the input and output voltages ior variations in irequency of the source 3. Reslstanoes 3 and l are chosen to have a. very small time constant. thereby complying with the condition oi s. negligible or very small time interval is: for the transition from one condltldn of control voltage to a second condition of control voltage.

Fig. 2 diagrammatically illustrates another embodiment of my invention in which a bridge-type circuit is also employed for controlling the phase of the output voltage in response to the voltage of the control circuit. A pair of serially connected resistances H and I! are connected across the conductors I and I or the output circuit, and the common juncture l8 thereof is connected to one terminal of the alternating current source 3. The bridge circuit comprises two parallel branches. one oi! which includes a rectifier l1 and the reslstance I4, and the other 01' which includes a rectifier l3 and the resistance ii. The rectlilers i1 and II are poled to energize selectively resistance I4 and IS in response to the polarity of the control voltage. I! desired, these rectlflers may be oi the bridge type and arranged to transmit alternating current. It will be noted that diagonal terminals l8 and II of rectifier I! are connected to the control circuit, and that the unidirectional conducting devices II, which constitute branches of the rectifier circuit, are poled to transmit current when the conductor 5 is positive relative to conductor 4. 0n the other hand. unidirectional conducting devices 22 01 rectifier II are connected in a manner to conduct current when the reverse condition exists, that is, when the conductor I is positive in potential relative to conductor 3. Diagonal terminals 23 and II 01' rectifier it are connected to the input circuit. and the other diagonal connections are connected in circuit with resistance II and the source 3.

The rectifier-s l1 and I 8 are also arranged to transmit alternating current, provided by the source 3. through the resistances i4 and i3. It is to be noted that in the arrangement of Fig. 2 it is permissible to omit the auxiliary source of biasing voltage or current.

The embodiment of my invention shown in Fig. 2 operates to control the phase of the alternating voltage supplied to the output circuit in response to th polarity of the voltage of the control circuit. This shift in phase is obtained by combining the alternating component of voltage produced by source 3 with the unidirectional component or voltage appearing across resistances l4 and I I which are produced hy transmitting umdirectional current through these resistances.

Rectifiers I! and [3 are selectively responsive to the polarity of the control voltage inasmuch as these rectlflers are oppositely poled. Rectifiers l1 and II also serve as paths for transmitting the flow of alternating current provided by source 3 through resistances ll and Hi. When the voltage 0! the control circuit is oi one polarity, as for example when conductor 6 is positive relative to conductor I, unidirectional current is transmitted through resltance II to shift the phase of the dutputvoltage in one direction relative to the voltage of the supply circuit 3, and when the reverse polarity condition exists, that is when conductor I is positive relative to conductor 5, rectifier I8 transmits unidirectional current to the resistance ll, shitting the phase of the voltage of the out- ,put circuit in the opposite direction with respect to the voltage 0! the source 3. The variation in the iciative amounts of current transmitted through the resistances l4 and I5 controls the amount by which the output voltage is shifted in phase relative to the voltage of the source 3.

In the embodiment of my invention shown in Fig. 3. instead oi employing a single source of alternating current I provide a pair of sources of alternating current 25 and 2B in order that the two branches of the control system may b independent, therehy minimizing the circulatin currents in the rectlflers I1 and I 8. Other corresponding elements have been assigned like reference numerals. It will be noted that I connect more the resistances I4 and i! transformers 21 and 23, respectively, and which are connected in a manner so that the output voltage is altemating.

The embodiment 01' my invention shown in Fig. 3 operates in substantially the same mannor as that explained above in connection with the arrangement shown in Fig. 2, with the exceptlon that the provision. of separate sources of alternating current 25 and it minimizes the ma gnitude of the rculating currents which flow through the root ers i1 and II.

In Fig. 4 there is illustrated a still further embodiment of my invention in which a bridgetype circuit is also employed i'or controlling the phase of the voltage of the output circuit including conductors l and 2. I provide in Fig. 4 an arrangement for transmitting unidirectional current through a pair of impedance elements, such as resistances 29 and 30, in response to the polarity of the voltage of the control circuit. The source of alternating current 3 is connected between the common juncture II of resistances I and II and the common juncture 3| of resistances I! and 33. In order to transmlt selectively unidirectional current to resistances 23 and 30 in response to the polarity of the voltage of the control circuit, I provide two pairs 02 serially connected unidirectional conducting devices such as rectiflers 32, 33 and 34, 35 having common Junctures 36 and 31, respectively. The two pairs 01' unidirectional conducting devices are oppositely poled with respect to the control circuit, and the common Junctures 33 and 31 are connected to opposite terminals of resistances 23 and 30. In addition, the pairs of unidirectional conducting devices also transmit the alternating current provided by source 3 through the resistances 21 and 30, so that the voltage appearing across the outside terminals 0! these resistances and the voltage impressed on the output circuit is an alternating voltage.

The operation of the embodiment of my inthe Output voltage is shifted in one direction Fll'ri'l respect to the voltage 01 source S. For a control voltage of opposite pola ty. the output voltage is shifted in the opposite. direction.

While in the above embodiments of my invention it will be cs 1 1i tliatthere is some variation in magnitude of the alternating volt- 5 age impressed across the output circuits which occurs coincidentally with the variation in phase relationsl'up'of': the output voltage with. respect tothe alternating currcnt'At will be appreclated that by slants of the circuitihis variation in magnitude a desired and unobiectionable range. of course, it is to besmderstood that in some applicatlonsit is required not only to obtain a change inphase relntilanslnn iniidirectionai current to phase diswith the voltase of an associated control c ir-r cult, but it is also desirable tocbtain a varie tiorrinniagnitude. It is to BEE the above described circuit srrangementsrcsn be designed to obtain both varintlonQ and variation in magnitude in: the magnitude and polarity of the. oltagend an associated control circultr r r is c 7 While I have snown and described misreation as :tocpsrticular systems oi connections and ac ompanying various devices diegrammoticallyshowmit will be obvious to those skilled in the art that changes en modificatheproper oholce ot the eontions may be made without departing from my V invention, and I, therefore, aim in the appended claims to cover all such changes and modifications as fall within the true, spirltand scope of my invention. 7 r a; r

What I claim as new anddesire$sure by Letters Patent oi theilnitci is:

L In combination, acontrol circuit for produchig a variable control voltage. on output circuit, means for alternating voltage, means connected betweensaid control circult and the last mentioned means for control- 5g.

ling the Ilf fliiilfiifiifi impressed on said output circuit with respect to said alternating voltage and in response to said control voltage and comprising a bridge circuit having a pair of parallel non-reactiv branches each including an impedance element, and impedance means connected to said control circuit for controlling the current through said impedance elements in response to said control voltage.

2. In combination, a control circuit for producing a variable control voltage. a source oi alternating current, on output circuit, means connected to said control circuit and said source for supplying to said output circuit on alternating voltage of variable phase relation with re- 65 spect. to the voltage of said source comprising a bridge circuit having a pair of parallel nonreactive branches each including an impedance element, said source of alternating current being connected in circuit with both of said branches,

and means for supplying to said branches unidirectional current to control the phase displacement of the voltage of sold output circuit I with respect to the voltage of said source.

3. In combination, a control circuit for pros minis-Jan e c n voltage, ss s alt-craze on; an output circiutnniesiosr conned nsaidcontrol cireuit agsd sgid source. for su gpiyingc to said output oircult an alternating voltage or variable phase relation to the voltage of saidsolg'ceand respgrag to the polarity o; the. voitsse of said gigs; circuit and comprising; bridge circuit, a pair of non-reactive branch circuits, 7 source of alternating current being connected in circuit with both of said branch circuits, and means for supplying to said branch circuits unidirectional current to control the phase displacement oi the voltage oi said output circuit witli'respect to the voltage of said source.

4% inconibination, a. control circuit in: producing s rarisbiecontrol voltage, ascurce oi alternoting an output circuit snd conn tecesoisoidcontrol circuitous sol-.dsource for supplying to said output circuit an alternating voitgseoi rariable phase relationwith respect to the rulings oi'said source lil an 81b clusiveiy resistance bridxe connected to said source and means for supplying'to soid bridge characteristic, an output circuit connected to the common juncture: o! the linear resistances and the resistances in said parallel brnnches a; source of alternating current, and

a sourceordireet current connected in series re-V;

lotion between the common juncture of the first mentioned resistances and said parallel branches, the variations lnpelarityot the voltage or said eontrol meult serving to control the phase oi tnc'voltage shield output circuit witnrespeg to. there! orssid source of alternating currents:

6. In combination, a control circuit for produoing a unidirectional voltageo! either polarity. asoureeoi alternating current, on output circuit, and 101' impressing on said'output circuit a voltage of variable phase relation with respect to the voltage of said source oi alternating current and comprising a bridge circuit including a plurality of branches each having a serially connected linear resistance and a resistance having a nonlinear impedance-current characteristic, the output circuit being connected'to the common iunctures of the linear and nonlinear resistarises in said parallel branches, a pair of resistances connected across said control circuit and a source oi unidirectional voltage connected in series relation with said source of alternating current, said source of alternating current and said source 0! unidirectional current being connected between the common iuncture o! the last mentioned resistances and the juncture or said parallel branches.

1. In combination, a control circuit for producing a unidirectional voltage of either polarity, a source of alternating current, an output circuit, and means connected between said control circuit and said source for supplying to said output circuit an alternating voltage of variable phase relation with respect to the voltage of said source and comprising a bridge circuit having a pair of parallel non-reactive branches each including in series relation a resistance and a rectifier, the rectifiers being connected to said control circuit and said output circuit being connected across said resistances.

8. In combination, a control circuit for producing a unidirectional voltage of either polarity, a source of alternating current, an output circult, means connected to said control circuit and said source for supplying to said output circuit an alternating voltage of variable phase relation in response to the voltage of said control circuit and comprising a bridge circuit including a pair of parallel non-reactive branch circuits each including in series relation a rectifier and a resistance, said source of alternating current being connected in circuit with both of said branches and said rectifiers being connected in said control circuit to energize selectively said resistances in response to the polarity of the voltage or said control circuit.

9. In combination, a control circuit for producing a unidirectional voltage oi. either polarity, a source of alternating current, an output circuit, and means for supplying to said output circuit an alternating voltage or variable phase relation in response to the voltage of said control circuit and comprising a bridge having a pair of parallel branches each including in series relation a resistance and a rectifier connected in said control circuit, said rectifiers being poled to be selectively responsive to the polarity of the voltage of said control circuit and to permit the flow oi alternating current from said source through the resistances in both of said parallel branches.

10. In combination, a control circuit for producing a voltage of reversible polarity, a. source of alternating current, an output circuit, and means for supplying to said output circuit an alternating voltage of variable phase relation in response to the voltage of said control circuit and comprising a bridge having a pair of Parallel branches each including in series relation 9, resistance and a rectifier connected in said control circuit, said rectifiers being of the full wave type to supply alternating current to the resistance from said source,

11. In combination, a control circuit for producing a voltage of reversible polarity, an output circuit, means for producing an alternating voltage, and means for controlling th phase of the voltage impressed on said output circuit with respect to said alternating voltage and in response to the voltage of said control circuit and comprising a pair or electric circuits connected to the means which produces the alternating voltage and each comprising an impedance element, a pair of rectifiers both connected to said control circuit and being oppositely poled to energize selectively said impedance elements by transmitting thereto unidirectional current in response to the polarity of the voltage of said control circuit.

12. In combination, a control circuit for producing a voltage of reversible polarity, an output circuit, means for producing an'alternating voltage, and means for controlling the phase of the voltage impressed on said output circuit with respect to said alternating voltage and in response to the voltage of said control circuit and comprising a pair of electric circuits each including an impedance element, a pair of rectifiers both connected to said control circuit and being poled to energize selectively said impedance elements by transmitting thereto unidirectional current in response to the polarity of the voltage of said control circuit.

13. In combination, a control circuit for producing a voltage of reversible polarity, a source of alternating current, an output circuit, a pair of serially connected resistances connected across said control circuit, and means for controlling the phase of the voltage impressed on said out-- put circuit in response to the voltage of said control circuit and comprising a second pair of serially connected resistances connected to said output circuit, said source of alternating current being connected between the common junctures of the first mentioned pair of resistances and the second mentioned pair of resistances and means for selectively transmitting to the second mentioned resistances unidirectional current in response to the polarity of the voltage of said control circuit and comprising in series relation two pairs of oppositely poled unidirectional conducting devices, the common juncture of the unidirectional conducting devices in each pair being connected to opposite terminals of the second mentioned resistances.

LESLIE CARTER LUDBROOK. 

